464 Reports and Proceedings, 
my native mountainous country Scotland, and fully admitting that 
on adequate inclines ice and water must, during long periods, have 
produced great denudation of the rocks, I maintain that such reason- 
ing is quite inadequate to explain the manifest proofs of convulsive 
agency which abound all over the crust of the earth, and even are to 
be seen in many of the mines in the very tract in which we are 
assembled. ‘Thus, to bring such things to the mind’s eye of persons 
who are acquainted with this neighbourhood, I do not apprehend 
that those who have examined the tract of Coalbrook Dale will 
contend that the deep gorge in which the Severn there flows has 
been eaten out by the agency of that river, the more so when the 
deep fissure is at once accounted for when we see the abrupt sever- 
ance that has taken place between the rocks which occupy its oppo- 
site sides. In that part of Shropshire, the Severn has not worn 
away the rocks during the historic era, nor has it produced a deeper 
channel ; whilst in its lower parts it has only deposited silt and mud, 
and increased the extent of land on its banks. 
‘Then, if we turn to the district in which we were last assembled, 
the valley at Bath is known to be the seat of one of those dis- 
turbances to which my eminent friend Sir Charles Lyell candidly 
applied the term “ convulsion”; the hot. waters of that city having 
ever since flowed out of a deep-seated fissure, clearly marked by the 
strata on the one side of the valley having been upheaved to a height 
very different from that which they once occupied in connection with 
those of the other side. When, indeed, we look to the lazy-flowing, 
mud-collecting Avon, which at Bath passes along that line of valley, 
how clearly do we see that it never scooped out its channel! Still 
more, when we follow it to Bristol, and observe it passing through 
the deep gorge of Mountain-limestone at Clifton, every one must 
then be convinced that it never could have produced such an exca- 
vation. In fact, we know that, from the earliest periods of history, 
it has only accumulated mud, and has never worn away any portion 
of hard rock. 
‘Fyrom such data I conclude that we cannot apply to flat regions, 
in which water has no abrading power, the same influence which it 
exerts in mountainous countries; whilst we are also compelled to 
admit that the convulsive dislocations of former periods produced 
many of those gorges in which our present streams flow. To pass, 
indeed, from the environs of Bath and Bristol, and even from the 
less distant Coalbrook Dale, you have only to contemplate the tract 
which lies between Birmingham and Dudley, and endeavour to 
satisfy the mind as to the processes by which it has been planed 
down before the surface was covered by the Northern Drift; for 
the great dislocations which this tract has undergone, as proved by 
many subterraneous workings, must have left a highly irregular 
surface, which was so levelled by some very active causes as to obli- 
terate the superficial irregularities corresponding with the interior 
disturbances. In short, what was this great power of denudation 
which took place in a tract where there are no mountains whence 
powerful streams descended, and in which there are no traces 
